An online transaction with a merchant website is initiated and completed via a single input action by a user. An online transaction application retrieves a first portion of user credit card information from a first storage location and a second portion of the user credit card information from a second storage location, decrypts the first portion with a first decryption key and the second portion with a second decryption key, encrypts and temporarily stores the complete user credit card information, and publishes an order associated with user order information to a pub/sub message bus. In response to the order being published, a headless browser that is connected to the merchant website retrieves and decrypts the unified user credit card information; completes the merchant checkout process; and deletes, erases, or otherwise removes the temporarily stored complete credit card information.